A multi-sheet glazing unit has a hollow space formed between two adjacent glass sheets. The hollow space is formed by providing a spacer in the circumferential edge between two adjacent glass sheets. The multi-sheet glazing unit has a high heat insulating property and a sound insulating property.
Some of double glazing unit spacers are molded from a resin material. As the method for preparing a double glazing unit, there is the following method. This is a method wherein two glass sheets are relatively moved with respect to a die for injecting a resin material while the glass sheets are supported so as to have a certain gap maintained therebetween, and a resin material is injected into the peripheral edge between the two glass sheets to form a resin spacer.
In JP-A-7-17748, a conventional method for preparing a double glazing unit is disclosed. This method is as follows: Positioning rollers are provided between parallel edges at two sides of a unit of two rectangular glass sheets to maintain a certain gap between the two glass sheets. While the unit and a die are relatively moved in this state, a resin material is injected from the die to form spacers between parallel edges at the remaining two sides of the unit where the positioning rollers are not provided. Subsequently, the positioning rollers are removed, and the resin material is injected from the die to form spacers between the parallel edges at the two sides of the unit where the positioning rollers have been provided. This method fundamentally deals with two glass sheets in horizontal fashion.
However, this method raises the following problems. The spacers have connections at four locations since spacers are formed in the parallel edges at the remaining two sides of the unit of the two glass sheets after spacers have been formed in the parallel edges at the two sides of the unit. The presence of many connections in the spacers increases the frequency of degrading the air tightness in a hollow space. In that case, the glass sheets are apt to be clouded up since moisture comes into the hollow space. Additionally, the heat insulating property and the sound insulating property of the double glazing unit degrade.
In this method, it is necessary to maintain the gap by the positioning rollers and so on in order to deal with two glass sheets in horizontal fashion. The glass sheets, which are supported in horizontal fashion, are apt to have central portions deflected downwardly by their own weight. From this viewpoint, dealing with glass sheets in horizontal fashion is not appropriate for a method for forming a spacer by injecting a resin material into the peripheral edges between two glass sheets while maintaining a certain gap between the glass sheets.
A proposal is provided wherein a resin material is injected into the peripheral edge between two glass sheets to form a spacer therein while holding the two glass sheets in vertical fashion.
FIG. 16 is a side view showing an example of the method for preparing a double glazing unit, wherein two glass sheets are dealt with, being held in vertical fashion. FIG. 17 is a perspective front view as viewed from an upper left position in FIG. 16. Two glass sheets 1 and 2 are sucked by a plurality of suction pads 4 provided on a suction supporting frame 3 and are held in substantially vertical fashion on rollers 5 so as to maintain a certain gap therebetween. The faces of the glass sheets 1 and 2 sucked by the suction pads 4 are ones opposite to the confronting faces of the glass sheets 1 and 2. A supporting leg 3a of the suction supporting frame 3 runs along a guide (not shown). Thus, the glass sheets 1 and 2 move in a horizontal direction parallel to the faces of the glass sheets, maintaining the certain gap therebetween. A die 6, which injects a resin material, confronts edges of the glass sheets 1 and 2. FIG. 15 is an enlarged side view of the die 6. The die 6 has a receiving portion 8 formed therein to accept edges of the glass sheet 1 and 2. The die 6 is provided with retainers 9 for glass sheets, which get contact with the faces of the glass sheets 1 and 2 opposite to the confronting faces.
The receiving portion 8 of the die 6 has a central portion formed with a resin injection port 10, which is open toward an edge between the glass sheets 1 and 2 in touch with the retainers 9. The resin injection port 10 has a resin conduit 11 communicated therewith. The die 6 is connected to an extruder (not shown) through a resin supply tube 13 with a swivel joint 12. To the resin conduit 11 is supplied a resin material from the extruder. The die 6 can be vertically moved by a driving electric motor and the like along a linear rail (not shown) vertically provided. The die 6 can rotate at 90 deg. intervals about the axis of the die 6 by an electric motor and the like (not shown) (FIG. 15).
Now, the production step for a double glazing unit will be explained. The suction supporting frame 3 moves in the left direction. After the right vertical edges of the glass sheets 1 and 2 have passed under the die 6, the die 6 lowers. With the right vertical edges of the glass sheets 1 and 2 being supported by the retainers 9 in the receiving portion 8 of the die 6, the die 6 rises, injecting the resin material from the resin injection port 10. The resin material is injected into the right vertical edge between the glass sheets 1 and 2 by the rising operation of the die 6.
When the die 6 has risen to the upper ends of the right vertical edges of the glass sheets 1 and 2, the die 6 stops rising. When die 6 has stopped, the die rotates by 90 deg. in the counterclockwise direction. After that, the glass sheets 1 and 2 move in the right direction along with the suction supporting frame 3. Since the resin material is being injected from the resin injection port 10, the resin material is injected into the upper edge between the glass sheets 1 and 2 by the movement of the glass sheets 1 and 2.
Thus, the resin material is continuously injected into the peripheral edge between the glass sheets 1 and 2 to form a spacer having a single connection in the peripheral direction.
However, the production method for a double glazing unit stated above has the following problems. When the glass sheets 1 and 2 are large, the suction supporting frame 3 is required to be formed in a large size. When the glass sheets 1 and 2 are small as shown by a chain double-dashed line in FIG. 17, the number of the suction pads 4, which suck and hold the glass sheets 1 and 2, decreases which leads to unreliable holding of the glass sheets 1 and 2.
Additionally, the movement of the die 6 and the movement of the supporting leg 3a interfere with each other. Further, the glass sheets 1 and 2 have poor accuracy in maintaining the gap and in positioning.
It is an object of the present invention to provide a method and an apparatus for preparing a double glazing unit, capable of controlling the positioning of two glass sheets with good accuracy without having any interference with a die when moving the glass sheets with a certain gap maintained therebetween.